In the process of cutting or shearing a hair during shaving, the friction of the hair against the flanks of the cutting blade is an important aspect. Particularly, the ease of cutting is associated with said friction, and said friction affects the comfort experienced during shaving. Especially in the case of blade shaving, said friction may result in nicks and cuts on the skin. The comfort during shaving is also affected by the friction between the skin and other skin-engaging surfaces of the blade razor or electric shaver.
Therefore, it goes without saying that many attempts were made in the prior art to reduce the friction between skin and/or hair and the surfaces of a personal care device intended for slidably engaging the skin and/or hair of the user, especially but not necessarily in a wet environment, such as in the case of a blade razor. Several friction reducing measures have been proposed.
Reference is for instance made to U.S. patent application publication no. 2003/0096060. Said publication teaches a razor blade including a substrate with a cutting edge defined by a sharpened tip and adjacent facets, a layer of a hard (carbon) coating on the cutting edge, and an overcoat layer of a chromium-containing coating. The overcoat layer is coated with an outer layer of polytetrafluoroethylene (PTFE). Said outer layer is used to provide reduced friction.
Also in U.S. Pat. No. 3,754,329, razor blades are described comprising at least one cutting edge portion defined by two facet portions having a narrow included angle there between. At least a portion of each of the facet portions has an RF sputtered coating of a hard metal and/or a sputtered coating of an organic plastic material. Said organic plastic material is exemplified by polymers being hydrophobic and having low friction characteristics, such as a polytetrafluoroethylene or like fluorine- or chlorine-containing polymers or polyethylene.
Moreover, reference can be made to German “Offenlegungsschrift” 24 16 560, disclosing razor blades having a coating applied thereon to facilitate adhesion to a lubricant. The low friction materials described are hydrophobic materials like polytetrafluoroethylene, polypropylene, polyhexafluoro propylene, polychlorotrifluor ethylene and polyethylene.
Unfortunately, PTFE coatings or, more in general, coatings of other friction-reducing polymers of the types described in the two previous paragraphs, applied in a similar or corresponding way, wear relatively quickly when sliding over the skin under the influence of the mechanical load of hair and skin exerted during shaving. This leads to a reduction in shaving comfort over time.
It is an object of the present invention to provide personal care devices having one or more surfaces intended for slidably engaging the skin and/or hairs of the user, wherein the personal care devices have a prolonged lubricious effect, resulting in prolonged comfort while using the device.